A New Torque Observation Technique for a PMSM Considering Unknown Magnetic Conditions

A new technique to observe the electromagnetic torque of a permanent magnet synchronous machine based on flux linkage estimation considering unknown magnetic condition is presented in this article. The magnetic behavior uncertainties including permanent magnet flux, linear self-inductances, linear coupling-effect inductances, and magnetic saturations are taken into account as a set of new variables in the model of machine. Regarding the new model, an appropriate observer based on Kalman-like algorithm is proposed to observe those variables. Then, the variables are collected and used to estimate the flux linkages and consequently the machine torque. The observability as well as the stability of the observer for the proposed system is theoretically investigated. The simulation and experimental results are represented for different scenarios. They prove the effectiveness of the proposed method.